Fin tube heat exchangers including a plurality of heat transfer fins (hereinafter simply referred to as “fins”) arranged parallel to each other and a heat transfer tube penetrating through the fins are known well. Particularly, fins formed so that a peak and a trough are found alternately along an air flow direction is called “corrugated fins”, which are used widely as high performance fins.
As fins other than the corrugated fins, the fins described in Patent Literatures 1 and 2 are known. The fins described in Patent Literatures 1 and 2 are obtained by forming cut-and-raised portions called “louvers”. These fins are often called “louver fins” and widely used like the corrugated fins.